The present invention relates to pendulous accelerometers, in which the sensitive member, formed by a pendulum, is rebalanced, i.e. restored to a predetermined neutral or rest position whatever the acceleration which is exerted thereon within its operating range.
It relates more particularly to accelerometers of the type comprising a stator housing adapted to be secured to the object whose acceleration it is desired to measure, defining a cavity having two opposite faces perpendicular to a sensitive axis of the accelerometer and forming two electrodes, and comprising a pendulum formed by a disc of insulating material with parallel electrically conducting faces, confronting said faces of the stator, which disc is connected to the stator by a hinge allowing it to oscillate under the action of the accelerations directed parallel to the sensitive axis, and a detection circuit for measuring the imbalance of the capacities of the two capacitors each formed by one face of the cavity and the conducting face opposite the pendulum.
It is an object of the present invention to provide an accelerometer of the above-defined type which is simple in construction, low in cost and capable of operating for long periods of time without appreciable overheating.
According to the invention, there is provided an electrostatic pendulous accelerometer for measuring acceleration along a sensing axis, comprising: a stator defining an internal cavity; a pendulum consisting of an electrically insulating disc connected to the stator by hinge means allowing the pendulum to oscillate under the action of accelerations along said sensing axis; a pair of first electrodes formed on the opposite surfaces of said cavity perpendicular to said sensing axis; second electrodes disposed on the opposite sides of said disc, each confronting one of said first electrodes and in capacitive relation therewith; a detection circuit for detecting unbalance between the capacities of two capacitors each comprising one of the first electrodes and the confronting second electrode; a servo control circuit responsive to said unbalance for applying on said capacitors DC voltages creating electrostatic torques balancing the acceleration torque exerted on the pendulum; and circuit means for measuring the difference between the voltages applied to said capacitors for determining the value of the acceleration along the sensing axis.
The invention will be better understood from the following description of accelerometers which form particular embodiments thereof, given by way of examples. The description refers to the accompanying drawings.